We have established a protein chemistry facility which has already demonstrated that it can successfully serve the needs of a diverse group of investigators whose problems require either synthetic peptides or results from protein characterization, peptide separation, sequencing, or amino acid analysis. Amino acid analysis, in particular, plays an essential role in almost every aspect of the operation of this facility. Because our current analyzer is neither fast enough to keep pace with the large numbers of samples being submitted to our facility nor is it sensitive enough to cope with numerous projects at Yale University where the peptides of interest are available in sub-nanomole amounts, we are requesting funds to purchase a new Beckman Model 7300 Amino Acid Analyzer. Although we can already sequence peptides in the 50-500 picomole range on our gas phase sequencer, we cannot yet isolate peptides in high yield from similar amounts of proteolytic digests because there is currently no microbore peptide HPLC available. The Applied Biosystems Microbore HPLC that we are requesting is specifically designed to meet this need. During the last two years our facility has either determined in toto or assisted in studies that have resulted in complete amino acid sequences for at least 15 different proteins. In order to help to better relate the structures of some of these proteins, as well as that of numerous other proteins that are being studied at Yale, to their function we are requesting funds to purchase a sensitive spectrofluorometer. This instrument will allow the facility to accurately measure the effect of chemical modifications and in vitro mutagenesis on the stability of a variety of protein:nucleic acid complexes. In this way we will be able to better understand the biological implications of the protein structures that we have helped to elucidate.